1. Field of the Invention
This invention relates to an underfloor access housing providing access to a plurality of electrical services at one location in the floor, and more particularly to improved protective caps for outlet openings presented by the access housing.
2. Description of the Prior Art
A piston-cylinder assembly for gaining access to raceways through knockouts provided in the upper surface of the raceway is disclosed in U.S. Pat. No. 3,943,673 (LINDAHL et al). A method and structure utilizing a temporary plastic insert covered with adhesion-preventing coating, for forming a recess in a wall is disclosed in U.S. Pat. No. 3,418,767 (SEEGER). The cylinder of LINDAHL et al and the plastic insert of SEEGER present exposed surfaces flush with the surrounding concrete.
Protective caps for outlet openings presented by crossover ducts and underfloor access housings are well-known in the art. U.S. Pat. Nos. 2,975,559 (HEDGREN); 3,093,933 (SLINGLUFF) described protective caps for crossover ducts. U.S. Pat. Nos. 3,701,837 (FORK); 3,932,696 (FORK et al) describe protective caps for underfloor access housings.
In accordance with the above-identified prior art, a cup-shaped protective cap presents an upper peripheral edge which is spaced below the upper surface or screed line of the floor fill by a relatively short distance, for example one-eigth inch (3.2 mm). Activation of a particular cell is easily accomplished by breaking and removing the relatively thin covering layer of fill above the protective cap to expose the cap for removal.
Modern building constructions utilize composite beams and girders which because of their lighter section, depth and weight, have a tendency to deflect to a greater extent than non-composite beams and girders. For example, the dead load deflection at the center of a large bay can be as much as 13/4 to 2 inches. Because of the deflection, excess concrete may be poured to provide a substantially level floor surface. As a result, the thickness of the floor fill above the upper peripheral edge of the protective caps can exceed the normal one-eigth inch. The excess concrete over the protective caps is a detriment only when it is desired to remove the protective cap. That is, it is not possible to readily remove the covering layer of concrete from the protective cap. Instead, removal of the covering layer of concrete becomes an expensive, time-consuming operation. In some instances, the concrete at the periphery of the thus formed cavity spalls so badly that the periphery thereof must be regrouted. So far as is known, there is not presently a satisfactory economic way of removing the excess covering layer of concrete to gain access to the protective caps.